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BOSS starting problems. Please help.

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I am having what I think are two separate problems on a 2012 BOSS 302.
  1. Hard to start. Even after new battery, voltage seems to drop after a day or two and car barely starts. After starting, voltage is at approximately 14.5. So, I think alternator is OK.
  2. A couple of times “wrench” light stays on and car will not rev past about 2200 rpm.
MIL not on.
No trouble codes.
PLEASE HELP.
Thanks.
 

carver

breaker of wrenches
445
598
ontario
Sounds like a slow draw off the battery. Is there a light on inside or trunk? Have you done any after market wiring like stereo or such? Also make sure you have solid grounds not just at the battery terminal but at the other ends at body and engine.
 

302 Hi Pro

Boss 302 - Racing Legend to Modern Muscle Car
2,009
441
Southeast
I am having what I think are two separate problems on a 2012 BOSS 302.
  1. Hard to start. Define “Hard to Start”. So it cranks & cranks but wont start?


  2. Even after new battery, voltage seems to drop after a day or two and car barely starts. This indicates you have an excessive battery draw. Do you own a multi meter?

  3. After starting, voltage is at approximately 14.5. So, I think alternator is OK. Your Alt is fine.

  1. A couple of times “wrench” light stays on and car will not rev past about 2200 rpm. This might be an electronic Ignition issue.
Next, have you performed TSB’s for ignition timing? (Crank sensor) & looked at Cam phaser harness upgrades?

Has the 12 Boss been in storage? Any possible fuel issues?

Need more information.

MIL not on.
No trouble codes.
PLEASE HELP.
Thanks.
 

302 Hi Pro

Boss 302 - Racing Legend to Modern Muscle Car
2,009
441
Southeast
Sorry, as it appears as though I posted the above questions incorrectly

Plus Carver is correct, check all grounds.
 
Thanks. I have not tracked the car in several years but think I was up on all the TSBs. Have not replaced any of the harness. No aftermarket wiring (eg stereo). Gas is fairly fresh. Using an OBD reader i see voltage at about 9.X after a couple of days. Service techs up the street have had it for a couple of days. Did a draw down test and found nothing. Kept it overnight. Next morning, no problem. Kept it one more night. Next morning, difficulty starting. When I say hard to start I mean ending cranks very slowly then starts. They are still testing but say if there is an intermittent draw down it will be difficult to find.

Searching internet found someone saying the wrench and 2200 rpm problem could be electric throttle system. That problem is very intermittent. Ground problem — hmmmmmm could be.
 
Thanks. I have not tracked the car in several years but think I was up on all the TSBs. Have not replaced any of the harness. No aftermarket wiring (eg stereo). Gas is fairly fresh. Using an OBD reader i see voltage at about 9.X after a couple of days. Service techs up the street have had it for a couple of days. Did a draw down test and found nothing. Kept it overnight. Next morning, no problem. Kept it one more night. Next morning, difficulty starting. When I say hard to start I mean ending cranks very slowly then starts. They are still testing but say if there is an intermittent draw down it will be difficult to find.

Searching internet found someone saying the wrench and 2200 rpm problem could be electric throttle system. That problem is very intermittent. Ground problem — hmmmmmm could be.
Actually now that I think I did wire in some electric exhaust cutouts, but unplugged them when this problem appeared. Did not help. They are still unplugged.
 

Mad Hatter

Gotta go Faster
5,237
4,227
Santiago, Chile
This is not very logical and I dont know why it happens... But if I leave the car in the shop or garage, with the car unlocked, the next day the car has problems starting.... Killed two Braille batteries doing this...
 

carver

breaker of wrenches
445
598
ontario
This is not very logical and I dont know why it happens... But if I leave the car in the shop or garage, with the car unlocked, the next day the car has problems starting.... Killed two Braille batteries doing this...

Ya that's a strange one. I haven't had that. I can leave mine for weeks at a time unlocked in my shop with no issue.
 

JDee

Ancient Racer
1,797
2,001
Exp. Type
W2W Racing
Exp. Level
20+ Years
5 miles from Mosport
This is not very logical and I dont know why it happens... But if I leave the car in the shop or garage, with the car unlocked, the next day the car has problems starting.... Killed two Braille batteries doing this...

I have the same problem with a Braille B2015. There is a large parasitic draw on the S550, not sure about the 197. It's bad enough that I can't even leave my phone/OBD2 bluetooth unit plugged in between track sessions, typically 40 minutes, or that will kill the battery. I have just learned to live with it, mostly by having lots of guys around who I know well enough that they will push the old girl if she needs it.

Right @carver ??? :) :););)

At home I just take the neg off or leave it on a trickle charger.
 

xr7

TMO Addict?
706
821
Exp. Type
Autocross
Exp. Level
10-20 Years
Minnesota
You need to check the amp draw on the battery with the car off, the trick is having an ammeter in parallel with the ground so when you remove the ground cable the ammeter maintains the current flow. I don't know of hand what the typical parasitic draw is but I would start there and see what you get. You can pull fuses to maybe determine what circuit is the cause if you have a drain. A shorted diode in an alternator will kill a battery fairly quickly. Another reason you need to maintain the flow of current is some computers take time to shutdown and the problem could be that one is hanging up and not shutting down. Disconnecting the battery generally causes the computers to shut off and your done. You could start also by just pulling the ground cable, leave it sit for a couple of days and see what happens. You could even have a bad battery. This type of problem can be tough to diagnosis, perseverance is needed. This is the type of switch or something similar - WirthCo 20148 Battery Doctor Knife Switch for Top Post Battery
Good luck.
 

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